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HOXC8 regulates self-renewal, differentiation and transformation of breast cancer stem cells

Shah, Mansi; Cardenas, Ryan; Wang, Belinda; Persson, Jenny LU ; Mongan, Nigel P. LU ; Grabowska, Anna and Allegrucci, Cinzia (2017) In Molecular Cancer 16. p.1-19
Abstract

Background: Homeobox genes are master regulators of cell fate during embryonic development and their expression is altered in cancer. By regulating the balance between cell proliferation and differentiation, they maintain homeostasis of normal tissues. Here, we screened the expression of homeobox genes in mammary stem cells to establish their role in stem cells transformation in breast cancer. Methods: Using a Homeobox Genes PCR array, we screened 83 homeobox genes in normal cancer breast stem/progenitor cells isolated by flow cytometry. The candidate gene HOXC8 epigenetic regulation was studied by DNA methylation and miRNA expression analyses. Self-renewal and differentiation of HOXC8-overexpressing or knockdown cells were assessed by... (More)

Background: Homeobox genes are master regulators of cell fate during embryonic development and their expression is altered in cancer. By regulating the balance between cell proliferation and differentiation, they maintain homeostasis of normal tissues. Here, we screened the expression of homeobox genes in mammary stem cells to establish their role in stem cells transformation in breast cancer. Methods: Using a Homeobox Genes PCR array, we screened 83 homeobox genes in normal cancer breast stem/progenitor cells isolated by flow cytometry. The candidate gene HOXC8 epigenetic regulation was studied by DNA methylation and miRNA expression analyses. Self-renewal and differentiation of HOXC8-overexpressing or knockdown cells were assessed by flow cytometry and mammosphere, 3D matrigel and soft agar assays. Clinical relevance of in vitro findings were validated by bioinformatics analysis of patient datasets from TCGA and METABRIC studies. Results: In this study we demonstrate altered expression of homeobox genes in breast cancer stem/progenitor cells. HOXC8 was consistently downregulated in stem/progenitor cells of all breast molecular subtypes, thus representing an interesting tumour suppressor candidate. We show that downregulated expression of HOXC8 is associated with DNA methylation at the gene promoter and expression of miR196 family members. Functional studies demonstrated that HOXC8 gain of function induces a decrease in the CD44+/CD24-/low cancer stem cell population and proportion of chemoresistant cells, with a concomitant increase in CD24+ differentiated cells. Increased HOXC8 levels also decrease the ability of cancer cells to form mammospheres and to grow in anchorage-independent conditions. Furthermore, loss of HOXC8 in non-tumorigenic mammary epithelial cells expands the cancer stem/progenitor cells pool, increases stem cell self-renewal, prevents differentiation induced by retinoic acid and induces a transformed phenotype. Conclusions: Taken together, our study points to an important role of homeobox genes in breast cancer stem/progenitor cell function and establishes HOXC8 as a suppressor of stemness and transformation in the mammary gland lineage.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Breast cancer, Cancer stem cells, Differentiation, Homeobox genes, HOXC8, Self-renewal
in
Molecular Cancer
volume
16
pages
1 - 19
publisher
BioMed Central
external identifiers
  • scopus:85012964860
  • wos:000394125200001
ISSN
1476-4598
DOI
10.1186/s12943-017-0605-z
language
English
LU publication?
yes
id
2cc433ad-2431-4a2a-8a5c-980dcd37036b
date added to LUP
2017-02-27 10:30:05
date last changed
2018-01-07 11:52:55
@article{2cc433ad-2431-4a2a-8a5c-980dcd37036b,
  abstract     = {<p>Background: Homeobox genes are master regulators of cell fate during embryonic development and their expression is altered in cancer. By regulating the balance between cell proliferation and differentiation, they maintain homeostasis of normal tissues. Here, we screened the expression of homeobox genes in mammary stem cells to establish their role in stem cells transformation in breast cancer. Methods: Using a Homeobox Genes PCR array, we screened 83 homeobox genes in normal cancer breast stem/progenitor cells isolated by flow cytometry. The candidate gene HOXC8 epigenetic regulation was studied by DNA methylation and miRNA expression analyses. Self-renewal and differentiation of HOXC8-overexpressing or knockdown cells were assessed by flow cytometry and mammosphere, 3D matrigel and soft agar assays. Clinical relevance of in vitro findings were validated by bioinformatics analysis of patient datasets from TCGA and METABRIC studies. Results: In this study we demonstrate altered expression of homeobox genes in breast cancer stem/progenitor cells. HOXC8 was consistently downregulated in stem/progenitor cells of all breast molecular subtypes, thus representing an interesting tumour suppressor candidate. We show that downregulated expression of HOXC8 is associated with DNA methylation at the gene promoter and expression of miR196 family members. Functional studies demonstrated that HOXC8 gain of function induces a decrease in the CD44<sup>+</sup>/CD24<sup>-/low</sup> cancer stem cell population and proportion of chemoresistant cells, with a concomitant increase in CD24<sup>+</sup> differentiated cells. Increased HOXC8 levels also decrease the ability of cancer cells to form mammospheres and to grow in anchorage-independent conditions. Furthermore, loss of HOXC8 in non-tumorigenic mammary epithelial cells expands the cancer stem/progenitor cells pool, increases stem cell self-renewal, prevents differentiation induced by retinoic acid and induces a transformed phenotype. Conclusions: Taken together, our study points to an important role of homeobox genes in breast cancer stem/progenitor cell function and establishes HOXC8 as a suppressor of stemness and transformation in the mammary gland lineage.</p>},
  articleno    = {38},
  author       = {Shah, Mansi and Cardenas, Ryan and Wang, Belinda and Persson, Jenny and Mongan, Nigel P. and Grabowska, Anna and Allegrucci, Cinzia},
  issn         = {1476-4598},
  keyword      = {Breast cancer,Cancer stem cells,Differentiation,Homeobox genes,HOXC8,Self-renewal},
  language     = {eng},
  month        = {02},
  pages        = {1--19},
  publisher    = {BioMed Central},
  series       = {Molecular Cancer},
  title        = {HOXC8 regulates self-renewal, differentiation and transformation of breast cancer stem cells},
  url          = {http://dx.doi.org/10.1186/s12943-017-0605-z},
  volume       = {16},
  year         = {2017},
}